Check to see if your default items-per-page setting has changed in your search Customize menu.
Start with a search that returns lots of results, then click on the icon in the upper right that allows you to change between list or gallery view, and select "Customize".
From there you can change your default search settings. Those settings should be maintained until you clear your cookies. Once in a while eBay alters something that affects those settings, and you may need to restore them once more.
If you have trouble changing your settings and you are using an add-on called "eBay item location -- my country only" try disabling that add-on.
